lab test 2 Flashcards
test for food contamination
PEA + MSA
urine test from patient infected with staphylococcusq
PEA + MSA
urine test from patient infected with e.coli
EMB
stool sample from patient who may be infected with gram -, enteric bacteria
EMB + MAC
gram positive
staph.
micrococcus luteus
spore forming
bacillus subtilis
acid fast
mycobac. smegma
gram negative
e.coli
pseudomonas
serratia
which is more deadly; hyper or hypotonic?
hypertonic; bacteria loose water rapidly and plasmolyze
three ways gamma and UV are different;
- gamma penetrates and sterilizes while UV only sterilizes surfaces
- gamma ionizes all molecules struck (irreparable) while UV causes thymine dimers to disrupt replication and transcription (reparable)
- gamma requires large emitter and lead-lined chamber while UV can be found outside for free or bought cheaply
anitseptic
chemicals used to on humans
disinfectant
chemicals used on non living surfaces
antibiotics
naturally produced chemicals that kill bacteria either on the inside or outside of body
bacteriocidal
kills bacteria
bacteriostatic
inhibits further bacterial growth
reazuring in thioglycollate
red when oxidized, clear when oxygen free
generator in gas pak
releases CO2 and H2 - h2 bids with O and CO2 makes microaerophiles grow better
agar in thioglycollate
prevents diffusion of O2 into lower areas of tube - keeps oxygen up with Na thioglycollate
methylene blue in gas pak
blue when oxidized, clear when oxygen free
pAmp in transformation experiment
contained plasmid for antibiotic ampicillin resistance; transformation of sensitive cells to resistant cells
broad spectrum antibiotic
affects many CATEGORIES of organisms (such as gram – and gram +), by affecting structures and processes common to many bacteria, not just a few.
thermophile
high temp 40C to 100C
size of zone of inhibition factors;
- solubility in water based agar
- temp. of incubation
- size of molucle of agent
- time of incubation
- interaction between agent and agar
- diffusability of agent
What explanation can be given for the fact that an organism may grow best at one temperature, yet only produce a capsule at another temperature?
spore forming enzymes may work better at dif. temp. than normal enzymes
what do anaerobes produce?
o3 and h2o2
why is oxygen toxis to anaerobes?
they lack toxin neutralizing enzymes - superoxide dismutase and catalase
how do anaerobes survive in o2 environments?
self destruct and form spores
which mediums are selective?
MAC + PEA
MAC ingredient
crystal violet and bile salts
MSA ingredient
mannitol as sugar and pH indicator
blood ingredient
red blood cells
PEA ingredient
alcohol
EMB ingredient
lactose as sugar, pH indicator
Green/metallic on EMB plate
- E.coli
- gram neg
- lactose fermenter
grows well on PEA
- hardy
- gram pos
- cocci
-NOT strep
white colonies on MSA plate
staph.
grows well on MAC plate
gram neg
yellow agar on MSA plate
-mannitol fermenter
-likely staph. a
colorless on EMB plate
- gram neg
- NOT a lactose fermenter
cultural characteristics of Slant
amount, form, color, odor, transparency
cultural characteristics of Plate
size, shape, margin, elevation, color
how antibiotics kill bacteria
- cell wall interference
- block protein synthesis
- block metabolites
- inhibit nucleic acid synthesis
